Uses

Most literature sources are from Japanese and Chinese foreign-language publications, clinical studies are on the efficacy of magnolia bark extract (MBE) are limited. Documentation on the materials and extracts for several studies is also limited. In vitro and animal studies document potential efficacy as an antibacterial, anti-inflammatory, and anticancer agent, as well as for use with Alzheimer disease, depression, diabetes, and menopause.

Dosing

MBE is commercially available in the United States and throughout Europe. Dosage varies depending on the condition treated, with weight loss products containing MBE available mostly in powder form. Several strengths are available for Relora , a patented blend marketed as "a natural stress management supplement" that includes MBE. Dosing recommendations include taking a 300 mg capsule of Relora 2 to 3 times per day. One small, randomized, controlled study treated patients with one 60 mg tablet of MBE daily to help relieve menopausal symptoms.

Contraindications

Avoid use if hypersensitivity exists for any of the components in MBE. No absolute contraindication could be found in the medical literature.

Pregnancy/Lactation

Avoid use during pregnancy and lactation because of limited clinical data. An animal study found that honokiol and magnolol blocked uterine contractions in rat uterus.

Interactions

Drug-herb interactions are documented, and caution is advisable in patients self-medicating with MBE. Magnolol may interact with acetaminophen . Additive adverse reactions with antiplatelet medications may occur in patients also self-medicating with magnolol. MBE and honokiol may interact with benzodiazepines . Magnolol may stimulate corticosterone secretion or increase steroid medication concentrations. MBE may cause excess sleepiness, vertigo, and dizziness in patients taking muscle relaxants .

Adverse Reactions

No dermatologic adverse effects were documented with topical application of magnolol and honokiol. In one small clinical trial, a patient dropped out because of a number of adverse reactions, including heartburn, shaking hands, perilabial numbness, sexual dysfunction, and thyroid dysfunction.

Toxicology

Numerous documented medicinal properties are associated with 2 major phenolic constituents, magnolol and honokiol, from the stem bark of M. officinalis Rehd. Et Wils. , Concentration variations of magnolol and honokiol exist in bark sourced from different provinces in China, as recorded in The Pharmacopoeia of the People's Republic of China . The plant is primarily indigenous to China and found at elevations of 200 to 3,000 meters.

History

MBE has been used for over 1,000 years as a folk medicine in Asia. , In traditional Asian medicine, MBE has been prescribed for treating acute pain, headaches, diarrhea, allergies, asthma, and gynecological disorders. It has also been used to treat fever, anxiety, nervous disorders, depression, muscular pain, abdominal fullness, constipation, and thrombotic stroke. , , , In Chinese and Japanese folk medicine, MBE has been used to treat bronchitis and emphysema.

Chemistry

Uses and Pharmacology

Most literature sources are from Japanese and Chinese foreign-language publications, and clinical studies on the efficacy of magnolia bark extract are limited. Documentation on the materials and extracts for several studies is also limited. In vitro and animal studies document potential efficacy as an antibacterial, anti-inflammatory, and anticancer agent, as well as for use with Alzheimer disease, depression, diabetes, and menopause.

MBE may also have antimicrobial activity against Helicobacter pylori .

Anti-inflammatoryIn vitro and animal data

Magnolol reduced swelling and inflammation in edema induced by carrageenan, compound 48/80, polymyxin B, and reversed passive Arthus reaction in mice. When compared with dexamethasone, magnolol did not increase glycogen levels in the liver. The mechanism of action appears to involve reducing the levels of eicosanoid mediators rather than affecting glucocorticoid activity or steroid hormone activity from the adrenal gland. ,

Magnolol and honokiol exhibited central depressant effects by producing sedation, ataxia, muscle relaxation, and a loss of the righting reflex in young chicks. The compound 4-O-methylhonokiol (4-O-MH) promoted neurite outgrowth in a concentration-dependent manner in cultured embryonic neuronal cells. The compound also increased expression of neurotrophins, which are believed to promote neurite outgrowth. An ethanol extract of M. officinalis and 4-O-MH suppressed beta amyloid peptide (eg, Aβ1-42)-induced memory impairment in mice, perhaps by inhibiting neuronal cell death, and increased reactive oxygen species expression. The compound 4-O-MH may also inhibit activation of the mitogen-activated protein kinase (MAP kinase) pathway, which is important in neuronal cell death. An ethanol extract of M. officinalis and 4-O-MH improved memory impairment induced by scopolamine in a dose-dependent manner.

Magnolol induced apoptosis in human lung cancer CH27 cells through activation of signaling pathways responsible for cell death, including regulation of the Bcl-2 family proteins and release of cytochrome c from mitochondria into the cytosol, leading to activation of the caspase cascade.

Honokiol-hydrogel reduced the number of pleural tumor foci and prolonged survival time in malignant pleural effusion-bearing mice when compared with controls. The mechanism involved inhibition of angiogenesis, and histological analysis of the pleural tumors revealed application of the gel increased the rate of apoptosis.

DepressionIn vitro and animal data

A mixture of honokiol and magnolol at 20 and 40 mg/kg inhibited stress-induced decreases of serotonin in the frontal cortex, hippocampus, striatum, hypothalamus, and nucleus accumbens in mice. The mixture also increased serotonin metabolite levels in the frontal cortex, striatum, and nucleus accumbens at 40 mg/kg. Honokiol and magnolol also reduced elevated corticosterone concentrations and normalized hypothalamic-pituitary-adrenal hyperactivity and reduced platelet adenylyl cyclase activity by upregulating the cyclic adenosine monophosphate pathway.

Experimentally induced depression in mice was inhibited by magnolol and its metabolite hydroxydihydromagnolol. An ethanol extract of a traditional Chinese medicine containing M. officinalis exhibited antidepressant effects in mice similar to the effects of fluoxetine. In a stress-induced model in rats, the combination of honokiol, magnolol, and ginger oil exhibited antidepressant effects. Honokiol and magnolol increased serotonin levels in numerous brain regions, while ginger reduced gastric mucosa cholecystokinin and serum gastrin levels.

A small, controlled, randomized, multicenter study examined the effects of 2 formulations, one containing magnolia bark extract (60 mg) and magnesium (50 mg), in symptomatic menopausal women with sleep or mood alterations. The magnolia extract and magnesium combination appeared to be effective in reducing psychoaffective and sleep disturbances from menopause. A small pilot study examined the effects on body weight from a dietary supplement containing extracts of M. officinalis and Phellodendron amurense in 28 premenopausal women. The supplement reduced evening cortisol levels and may have improved systolic blood pressure as well as perceived stress. Another randomized, placebo-controlled trial indicated that the same dietary supplement may reduce mild transitory anxiety in premenopausal women.

Other pharmacologic activityAntioxidant

In vitro and animal studies document potent antioxidant activity for magnolol and honokiol in protecting against myocardial and cerebral ischemia by inhibiting neutrophil infiltration and reactive oxygen species production. , ,

Extracts of M. officinalis may have benzodiazepine -like activity as documented by a strong affinity on the benzodiazepine -binding site of the gamma aminobutyric acid (GABA) receptor . Honokiol also interacts with the GABA receptor and exhibited activity similar to that of diazepam . ,

Dosage

MBE is commercially available in the United States and throughout Europe, as documented by Internet search engines. Dosage varies depending on the condition treated, with weight loss products containing MBE available mostly in powder form. Several strengths are available for Relora , a patented blend marketed as "a natural stress management supplement" that includes MBE. Dosing recommendations include taking a 300 mg capsule of Relora 2 to 3 times per day. A small, randomized, controlled study treated patients with one 60 mg tablet of MBE daily to help relieve menopausal symptoms.

Pregnancy/Lactation

Avoid use during pregnancy and lactation because of limited clinical data. An animal study documented that honokiol and magnolol blocked calcium-dependent uterine oscillatory contractions in rat uterus.

Adverse Reactions

No adverse dermatologic effects were documented with topical application of magnolol and honokiol. In one small clinical trial, a patient dropped out because of a number of adverse reactions, including heartburn, shaking hands, perilabial numbness, sexual dysfunction, and thyroid dysfunction.

Toxicology

Dietary administration of MBE in rats at doses of up to 480 mg/kg in a 21-day study and 240 mg/kg in a 90-day study resulted in no clinically important toxicity. Some sources document the development of progressive interstitial renal fibrosis in patients consuming an herbal blend containing M. officinalis . , In vitro studies demonstrate no genotoxic effects from MBE in chromosomal aberration assays. One study documented that magnolol in liver graft preservation enhanced apoptotic events under cold preservation instead of preserving hepatocyte integrity.